The present invention relates to fabricating a semiconductor device and more particularly to X-ray lithography to form a fine pattern, for example, as used for making highly integrated memory devices.
Efforts have been made to develop X-ray lithography to be used in microfabrication and to be capable of manufacturing future highly integrated LSIs at high production capacity. Until now, development efforts have been focused on a 1:1 method, in which a mask of the same scale as the LSI is replicated. Since the replication performance depends on the mask precision, a reduced projection method is newly proposed in which a beam path intersects an enlarged mask, after, which the beam is reduced and exposed onto wafers. This is described in, for example, Technical Digest Series Volume of Soft-X-ray Projection on Lithography, p. 57-59, 1991. With this reduced projection method, because of the restrictions of a focusing optical system, the wavelength of the X-ray is about 130A, more than ten times longer than that of the conventional 1:1 method. For this reason, an entire system including an optical system and a wafer exposing unit is arranged in one high-vacuum chamber.